This invention relates to actions for musical instruments of the piano type. In particular, it relates to such actions wherein a hammer is activated and given rotational or pivotal momentum by the striking of a key such that the hammer strikes a tone generating means and then recoils or falls toward a rest position.
Numerous types of piano actions involving rotating or pivoting hammers and keys are well known in the art. Such actions are described, for example, in my U.S. Pat. Nos. 2,456,321 and 2,469,667.
One of the problems that has long plagued users of musical instruments of the piano type has been the problem of bouncing or rebounding hammers. I have addressed myself to this problem for more than thirty years and have made substantial improvements in piano actions to alleviate the problem (for example, as shown in my U.S. Pat. No. 3,270,608). However, with modern, highly sensitive sound generating and amplifying equipment, as used in quality electric pianos, the standards of performance have increased to the point where still additional improvements are desirable in order to produce highest quality pianos.
In a typical electric piano action, when the pianist strikes a key, the rear end of the key engages and thrusts a hammer so that the head of the hammer strikes the tine of a tone generating device, and the vibration of the tine is amplified and converted to audible sound. It is fundamental that the hammer must be in free rotational flight (that is, under no substantial pressure from the key) at the moment the hammerhead strikes the tine. This free rotational flight is essential, among other things, to prevent damping of the vibrations of the tine. Thus, it is essential that the upward motion of the rear of the key must terminate at a point sufficiently low that when it is engaged with the hammer at this point the head of the hammer is spaced slightly apart from the tine. In other words, when the key is fully depressed, it does not hold the hammerhead against the tine.
In practice, it has been found essential to design the piano action such that when the key is fully depressed, there is a substantial distance between the tine and the head of the hammer (after the hammer strikes the tine and recoils back into a stable position against the depressed key). This distance between the tine and the hammerhead is known as the escapement distance. Theoretically, the escapement distance need be no greater than the maximum deflection of the tine during its most extreme vibrations (i.e., a sufficient distance to keep the vibrating tine from being dampened by contact with the hammer). However, in practice it has been found that due to resilience in the action mechanisms, among other things, there is a tendency for the hammer to bounce or rebound from the escapement position upwardly to a position within range of the vibrating tine. This results in double-striking of the tine to superimpose consecutive tone generations on the system, and these are then amplified to create a distorted or imperfect musical product. Furthermore, since pianists can detect the movements and double-striking in their fingertips, it is distracting and disrupts their performance.
One solution to the bouncing, rebounding or double-striking problem is to design actions with large escapement distances sufficient to minimize the occasions when the hammer will bounce sufficiently to actually strike the tine twice on the same strike of the key. However, this does not prevent the distracting effect of the bounce on the pianist, and, furthermore, it interferes with certain styles of musical performance. For example, since the pianist can only exert control and power to the hammer during the pivoting motion of the key, it is highly desirable to continue the pivoting motion to the greatest possible extent (i.e., to design actions with the minimum feasible escapement distances). This is especially desirable for "soft" playing where the pianist does not enjoy the luxury of being able to strike the key heavily to impart substantial momentum to the hammer to carry it through the escapement distance to the tine.
The action described in my U.S. Pat. No. 3,270,608 completely eliminated double-striking of the tines under most circumstances by incorporating a braking surface on the key which cooperated with a portion of the foot of the hammer to substantially lock the hammer at the escapement distance from the tine when the hammer was fully depressed. However, under certain circumstances, it has been found that the problem of double-striking continues to plague pianists. The problem becomes particularly acute where sensitive actions are used with escapement distances of about 1/8" or less.
Another problem presented by actions in which there is even slight wiggling, bouncing, vibrating, or other irregular movements of the key or hammer occurs when auxiliary tone generators or synthesizers are used to give certain musical effects in addition to those generated by the vibrating tines. For example, to generate tones which are responsive in volume or pitch to the velocity of movement of the keys (rather than simply to the vibration of the tines), detecting devices to sense the movement of the keys must be used. Thus, for highest quality actions it is important to eliminate even slight movements of the keys which are not intended by the pianist. This means that the pianist must have the key movement totally under control throughout the pivoting action whether the key is being depressed or released, and the hammer is being impelled upwardly toward the tine or returning to rest position. There has thus been a need to provide a unitary means for controlling the key and hammer movements throughout their upward and downward cycles and especially when the key is at or near either its rest position or its fully depressed position with the hammer at its escapement position.
It has now been found that these and other objects can be achieved, and the problems of the prior art can be greatly alleviated or even eliminated, in accordance with the present invention.